Cardiac Hypertrophy in Transgenic Rats Expressing a Dominant-Negative Mutant of the Natriuretic Peptide Receptor B

Natriuretic peptides (NP) mediate their effects by activating membrane-bound guanylyl cyclase-coupled receptors A (NPR-A) or B (NPR-B). Whereas the pathophysiological role of NPR-A has been widely studied, only limited knowledge on the cardiovascular function of NPR-B is available. In vitro studies suggest antiproliferative and antihypertrophic actions of the NPR-B ligand C-type NP (CNP). Because of the lack of a specific pharmacological inhibitor, these effects could not clearly be attributed to impaired NPR-B signaling. Recently, gene deletion revealed a predominant role of NPR-B in endochondral ossification and development of female reproductive organs. However, morphological abnormalities and premature death of NPR-B-deficient mice preclude detailed cardiovascular phenotyping. In the present study, a dominant-negative mutant (NPR-BΔKC) was used to characterize CNP-dependent NPR-B signaling in vitro and in transgenic rats. Here we demonstrate that reduced CNP- but not atrial NP-dependent cGMP response attenuates antihypertrophic potency of CNP in vitro. In transgenic rats, NPR-BΔKC expression selectively reduced NPR-B but not NPR-A signaling. NPR-BΔKC transgenic rats display progressive, blood pressure-independent cardiac hypertrophy and elevated heart rate. The hypertrophic phenotype is further enhanced in chronic volume overload-induced congestive heart failure. Thus, this study provides evidence linking NPR-B signaling to the control of cardiac growth.